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A South Korean army soldier walks by a signboard showing the distance to North Korean capital Pyongyang and that for South's capital Seoul from Imjingang Station near the border village of Panmunjom in Paju, South Korea, Thursday, Feb. 14, 2013. North Korea's neighbors bolstered their military preparations and mobilized scientists Wednesday to determine whether Pyongyang's third nuclear test, conducted in defiance of U.N. warnings, was as successful as the North claimed.(AP Photo/Ahn Young-joon)

A South Korean army soldier walks by a signboard showing the distance to North Korean capital Pyongyang and that for South's capital Seoul from Imjingang Station near the border village of Panmunjom in Paju, South Korea, Thursday, Feb. 14, 2013. North Korea's neighbors bolstered their military preparations and mobilized scientists Wednesday to determine whether Pyongyang's third nuclear test, conducted in defiance of U.N. warnings, was as successful as the North claimed.(AP Photo/Ahn Young-joon)